sorry for the late input here, but in my experience, making a slurry of white flour and water and just leaving it out can just as easily result in green, purple & black slimy mold. you'll get surer results by enlisting the natural yeasts that inhabit the outer parts of grains, fruits, etc.
whole grain coarse ground rye flour will pretty dependably get you going, as well as organic grapes. i've also had good results with potato skins, but perhaps that was just luck.
unless you're using it daily, there's no need to feed it that often. after the initial love affair cools off, i think it's rare for most people (myself at least) to use it more than a few times a month for any extended period. i've never had any problems keeping mine in the fridge and feeding it once every week or two.
if you develop a starter that you just love, and plan on not using it for an extended period, you can pour some out on a cookie sheet lined with parchment, dry it out somewhat less than 100% (not by baking of course), break it up into a zip-lock bag, and keep it in the fridge for months. some people freeze it, but i've never tried.
besides bread, my favorite use is for sourdough buckwheat pancakes with maple syrup. just fabulous!
good luck with the batch you've got going.